1. Field of the Invention
This invention relates to a sliding door for a motor vehicle, the sliding door being movable by a sliding motion into an opened and a closed position, a main lock arrangement being provided by which the sliding door can be fixed in the closed position, and an additional lock arrangement being provided to support the main lock arrangement when the sliding door is being fixed in the closed position. The invention also relates to a lock arrangement for such a sliding door.
2. Description of Related Art
Here, the term “sliding door” combines all components which are necessary for the functionality of a sliding door. They include, in addition to the movable component, also the corresponding frame which is provided in the motor vehicle body, guide rails which may be present, etc. Hereinafter, the concept “sliding door”, wherever it is used for simple readability, is also used synonymously with the concept “movable component.”
Sliding doors have been used for a long time for delivery trucks and vans and recently also for passenger vehicles. It is common to all sliding doors that they can be moved by a sliding motion into an opened and a closed position. This sliding motion takes place essentially parallel to the side wall of the motor vehicle. The fact that it is possible to load and unload and to get in and out without difficulty is especially advantageous.
Numerous versions are known for design implementation of the movement kinematics of a sliding door. They include, for example, the principle of rail guidance to which optionally a lever arrangement is added. Here, the special construction of the movement kinematics is not important. Rather, the approach in accordance to the invention can be applied to all conceivable constructions. Nor is it important where the sliding door on the motor vehicle is located, so that sliding doors located both laterally and also on the back on the motor vehicle are encompassed.
In particular, when using sliding doors for passenger cars, the guarantee of reliable fixing of the sliding door in the closed position acquires increasing importance. Unintentional opening of the sliding door, for example, by a force which acts from the inside perpendicularly on the sliding door, leads to considerable danger for the motor vehicle passengers.
At the same time, demands for convenience of use are steadily increasing. This includes, for example, the function of fixing the sliding door in the opened position so that the sliding door does not close independently when loading and unloading and when getting in and out. This function is necessary mainly when the motor vehicle is on a slope such that the weight of the sliding door presses in the closing direction.
The known sliding door underlying the present invention (U.S. Pat. No. 4,662,109) shows one approach to ensuring the secure fixing of the sliding door. In this case, a rail-guided sliding door is used which has a main lock arrangement on the side of the sliding door which is at the rear viewed in the direction of travel and an auxiliary lock arrangement on the side of the sliding door which is the front viewed in the direction of travel. The auxiliary lock arrangement supports the main lock arrangement when the sliding door is fixed in the closed position. This is advantageous especially when a force is acting perpendicularly on the sliding door from the inside toward the outside, since this force is accommodated via three points of force application, specifically the main lock arrangement, the rail guide and the auxiliary lock arrangement. Furthermore, the auxiliary lock arrangement opposes the movement of the sliding door in the opening direction, therefore essentially along the direction of travel. In one embodiment, the main lock arrangement has, as the latching elements, a conventional latch and ratchet, while the auxiliary lock arrangement is implemented by a simple hook. In normal operation, the main lock arrangement accommodates the largest part of the holding force necessary for fixing the sliding door in the closed position. The disadvantage in this known sliding door is the fact that the ease of use is comparatively poor. This is due, among other reasons, to the fact that there is no fixing of the sliding door in the opened position.
Another known sliding door (German Patent Application DE 2 347 702 A1) has, in addition to the main lock arrangement, a fixing arrangement by which the sliding door can be fixed in the opened position. The fixing arrangement is provided with a pivotable journal which is located on the movable component of the sliding door and engages a hook-shaped recess when the sliding door is moved into the opened position, thus preventing the sliding door from moving backward. The disadvantage in this sliding door with a fixing arrangement is the poor security against unintentional opening of the sliding door out of the closed position.
The same applies to the known sliding door of UK Patent Application GB 2 210 339 A which has a main lock arrangement for fixing the sliding door in the closed position and a fixing arrangement for fixing the sliding door in the opened position. Here, the security of fixing of the sliding door in the closed position against unintentional opening is small. In one embodiment, the main lock arrangement, at the same time, assumes the function of a fixing arrangement, by which the construction effort is reduced. This does not lead to an optimum solution with respect to the construction of the components involved, since the holding forces when the sliding door is in the opened position are much smaller than when the sliding door is in the closed position.
A corresponding combination of the aforementioned two functions, specifically the fixing of the sliding door in the closed position and the fixing of the sliding door in the opened position, is also shown by another known sliding door (U.S. Pat. No. 5,520,423) which has a system of two latches. The two latches are each assigned to the two aforementioned functions. Here, in any case, the problem of optimum construction also arises.